Non-equilibrium steady-states in a driven-dissipative superfluid

TL;DR

This paper experimentally investigates a driven-dissipative Bose-Einstein condensate in a Josephson junction array, revealing phase transitions, bistability, and critical slowing down in non-equilibrium steady states.

Contribution

It demonstrates the controlled realization of non-equilibrium steady states and phase transitions in a driven-dissipative superfluid system using cold atoms.

Findings

Transition from superfluid to resistive state with increasing dissipation

Observation of bistability between superfluid and resistive states

Critical slowing down indicating a non-equilibrium phase transition

Abstract

We experimentally study a driven-dissipative Josephson junction array, realized with a weakly interacting Bose Einstein condensate residing in a one-dimensional optical lattice. Engineered losses on one site act as a local dissipative process, while tunneling from the neighboring sites constitutes the driving force. We characterize the emerging steady-states of this atomtronic device. With increasing dissipation strength $\gamma$ the system crosses from a superfluid state, characterized by a coherent Josephson current into the lossy site to a resistive state, characterized by an incoherent hopping transport. For intermediate values of $\gamma$, the system exhibits bistability, where a superfluid and a resistive branch coexist. We also study the relaxation dynamics towards the steady-state, where we find a critical slowing down, indicating the presence of a non-equilibrium phase transition.